1. Field of the Invention
The present invention relates to a series (and a series group) of orthogonal gear reducers with motors capable of securing a large number of combinations between the required load capacities and reduction ratios while lessening the kinds of the motors and gear boxes to be prepared. The present invention may be embodied in the applications of physical distribution equipments, particularly, conveyors or the like.
2. Description of the Prior Art
Recently, in the market of physical distribution equipments, particularly, conveyors or the like, there has been an enhanced need for orthogonal gear reducers with motors, each of which includes a motor and makes the output shaft orthogonal to the motor shaft.
The reason why the reducer mounted with a motor is required is as follows:
Namely, for example, in the physical distribution system which constituted of a plurality of conveyors, efficiency is increased by only operating the required parts are operated when. In this case, it is desirable to independently drive the conveyors. Also, in changing the arrangement of the individual conveyors, which is often carried out for modifying the conveying path, it is advantageous to independently drive the conveyors.
On the other hand, the reason why the orthogonal gear reducer is required is as follows:
Namely, the orthogonal gear reducer with a motor generally has the maximum dimension (longitudinal dimension) in the direction of the motor shaft. Accordingly, for enhancing the space performance in mounting the gear reducer, the gear reducer is desired to be disposed in such a manner that the direction of its maximum dimension (the direction of the motor shaft) is parallel to the conveyor. On the contrary, for driving the shaft of the conveyor, the output shaft of the gear reducer must be paralleled to the shaft of the conveyor. Consequently, the output shaft of the gear reducer must be disposed orthogonally to the motor shaft.
The present applicant has been proposed such an orthogonal gear reducer with a motor as satisfying the above requirement in Japanese Patent Laid-open No. sho 62-283044 (Japanese Patent Publication No. hei 2-53656) which is Japanese Patent Laid Open No. 1-126468, and put it on the market. The known example is shown in FIGS. 14 and 15.
The orthogonal gear reducer with a motor of the known example includes a hypoid gear set 20 at a first step, and the combination of parallel shaft gears 21 at a second step or more. Thus, by changing the combination of the parallel shaft gears 21, the reduction ratio can be changed.
Therefore, in order to meet the various requirements of users, a plural of "sub-series" (hereinafter,referred to as "frame number") are previously prepared. Namely, the fitting dimensions (mounting sizes) to the mating machine determined by the size of the output shafts and the gear boxes are classified into several kinds (from "small" to "large") to define several kinds of frame numbers, in accordance with the market requirement. Further, in the same frame number, several kinds of reduction ratios are previously systematized. Thus, by preparing a series constituted of the above frame numbers, it is possible to meet the various requirements of users.
However, the series of the known example shown in FIGS. 14 and 15 has the following inconvenience: Namely, in the series, one motor 1 is prepared in one frame number, and a special gear box 2 is prepared for each reduction ratio required in the same frame number, and accordingly, in the actual circumstances, the number of the parts for common use is very small as the whole series.
To increase the number of parts for common use as large as possible, there has been proposed such a series as shown in FIGS. 16 to 19.
Namely, in general, the gear reducer, which includes the orthogonal gear reducer with a motor, is used in order to reduce the rotation of the motor to be the optimal rotational speed required for the mating driven machine. When the sizes of the output shaft and the gear box of the reducer are determined by the frame number, the limit of the mechanical strength (allowable output torque) is approximately determined. Consequently, even in the same frame number, the following combination is preferable for the strength balance between the output shaft and the reduction ratio: a large capacity motor is combined with a gear box of a low reduction ratio (the rotational ratio between the motor and the output shaft is small), while a small capacity motor is combined with a gear box of a high reduction ratio (the rotational ratio between the motor and the output shaft is small).
Accordingly, for light weight and compactness, it is preferable to perform the serialization by combining motors having two kinds or more of the capacities in one frame number.
On the other hand, as shown in FIGS. 14 and 15, in the orthogonal gear reducer with a motor using a hypoid gear set 20, for achieving the compactness as a whole, a hypoid pinion 4 is generally formed integrally with a motor shaft 3.
In the hypoid gear set 20, an outside diameter d1 of a hypoid pinion 4 and an outside diameter D1 of a hypoid gear 5 are determined depending on the transmission amount and the reduction ratio. Further, based on the balance thereof, an offset amount e1 is determined.
As a result, depending on the strength balance between the hypoid gear 4 and the whole, a dimension (size) of a bearing 13 on the motor shaft load side and an axial interval A1 between the bearing 13 and the center C of the hypoid gear 5 are determined.
Under the above requirement, in the examples as shown in FIGS. 16 and 19, the following serialization is achieved by combining two kinds or more of the motors in one frame number.
FIG. 16 shows an example of combining a small capacity motor 1a with a high reduction ratio gear box 2a including a hypoid gear set 20a combined with two steps of parallel shaft gears 21a. FIG. 17 shows a development of the gear train thereof.
FIG. 18 is an example of combining a large capacity motor 1b with a low reduction ratio gear box 2b including a hypoid gear set 20b combined with a one step of parallel shaft gear 21b. FIG. 19 is a development of the gear train thereof.
Each example described above belongs to the same frame number. As shown in FIG. 17 (19), a wall surface 23a (23b) of the motor 1a (1b) on the gear box side is formed integrally with the gear box 2a (2b). A bearing 13a (13b) on the motor shaft load side is contained in a housing 24a (24b) provided on the wail surface 23a (23b).
The hypoid gear sets 20a (20b) having the different sizes are prepared for respective capacities of the motors 1a (1b). The high reduction ratio gear reducer, which is smaller in the motor capacity, is combined with the hypoid gear set 20a with a small size (see FIGS. 16 and 17). On the other hand, the low reduction ratio gear reducer, which is larger in the motor capacity, is combined with the hypoid gear set 20b with a large size (see FIGS. 18 and 19).
Also, while not being shown, as for the motor shafts 3a (3b) integrally formed with the hypoid pinions 4a (4b), the motor shaft for a large capacity belonging to the frame number in the figure may be used for a high reduction ratio in the higher frame number. On the other hand, the motor shaft for a small capacity belonging to the frame number in the figure may be used for a low reduction ratio in the Lower frame number. Thus, in the series, it is possible to number of kinds of the motor shafts 3a(3b).
However, even in the series of the examples as shown in FIGS. 16 to 19, in the same frame number, the gear boxes 2a and 2b differ in the offset amounts &lt;ea&gt; and &lt;eb&gt;, the bearings 13a and 13b on the motor shaft load side and in the axial intervals Aa and Ab of the hypoid gears 5a and 5b. As a result, there must be prepared the gear box 2a exclusive for a high reduction ratio (three-step type), and the gear box 2b exclusive for a low reduction ratio (two-step type). Accordingly, the parallel shaft gear trains 21a and 21b cannot be used in common.
That is, even in the conventional series relating to the combination of the gear boxes and the motors as shown in FIGS. 16 to 19, there has been significantly arisen a disadvantage of not sufficiently coping with the diversification and the cost reduction of the orthogonal gear reducers with motors generated by the rationalization of the recent production system.
Concretely, in the physical distribution system frequently using the gear reducers, it is efficient that the required parts of the physical distribution system constituted of a plurality of conveyors are operated when required, and accordingly, the conveyors are intended to be independently driven.
However, the orthogonal gear reducer with a motor used for a conveyor constitutes only part of a mating machine (conveyor or the like), and further, the mating machine constitutes only part of the whole physical distribution system. Accordingly, in the viewpoint of the whole physical distribution system, there are required various mounting (fitting) methods and reduction ratios, for containing the orthogonal gear reducers with motors and for obtaining the optimal output torque and the output rotational frequency.
For example, the orthogonal gear reducers with motors are required in the physical system to be used in the following various mounting methods, various combinations of the motor capacities and various reduction ratios. The above mounting methods involve: a) a foot mounting type of fitting the gear reducer to the mating machine at the floor surface parallel to the output shaft of the gear box; b) a flange mounting type of fitting the gear reducer to the mating machine at the surface right to the output shaft of the gear box; and c) a hollow-shaft type of making the output shaft of the gear box to be hollowed, and passing the gear box through the hollow portion, thereby directly connecting the gear reducer to the input shaft of the mating machine.
However, in the series according to the conventional combination of gear box and motor, there has arisen a disadvantage of requiring the kinds of the gear boxes corresponding to those of the combination of the motor capacities in the same frame number.
In general, the gear box occupies a large capacity in the whole orthogonal gear reducer and is large in weight, and further, requires a large number of the machining processes. Accordingly, increase in the kinds of the gear boxes to be prepared as stock directly leads to cost rise.
Also, in the viewpoint of the whole physical distribution system, the orthogonal gear reducers with motors are often required to be changed in the reduction ratio and motor capacity. However, in the conventional series, the change in the motor capacity necessarily needs the change in the gear box, and consequently, the whole gear reducer must be exchanged. This results in the useless spending to users.